Objective: To observe the effects of candesartan on the expressions of JAK2 and protein tyrosine phosphatase-1B (PTP-1B) in adipose tissue of obese rats induced by high-fat diet.
Methods: A total of 45 male Wistar rats were randomly assigned into 3 groups of normal control (NC group), high fat diet (HF group) and high-fat diet with daily Candesartan treatment (FC group). The rats of FC group were treated with orally taken Candesartan at a dose of 8 mg/kg body weight per day. Blood chemistry and insulin were assayed at Week 16. Euglycemic-hyperinsulinemic clamp technique was performed to evaluate the peripheral insulin resistance. The expressions of JAK2 and PTP-1B in adipose tissue were confirmed by both reverse transcription-polymerase chain reaction (RT-PCR) and Western blot.
Results: (1) The body weight and peri-renal fat weight of HF group were significantly higher than those of FC and NC groups (all P < 0.05). (2) total cholesterol (TC) and fasting insulin (FINS) of FC group were lower than those of HF group [TC, FC group: (1.37 ± 0.39) mmol/L vs HF group: (2.01 ± 0.26) mmol/L, P < 0.05; FINS, FC group: (3.03 ± 1.37) mU/L vs HF group: (4.76 ± 2.75) mU/L, P < 0.05] while insulin sensitive index (ISI) and angiotensin II (AngII) of FC group were much higher than those of HF group [ISI, FC group: (58 ± 12) × 10(-3) vs HF group: (29 ± 9) × 10(-3), P < 0.05; AngII, FC group: (61 ± 11) mmol/L vs HF group: (52 ± 10) mmol/L, P < 0.05]. (3) The steady-state glucose infusion rate (SSGIR) of FC group was significantly higher than that of HF group [FC group: (22 ± 5) mg×kg(-1)×min(-1) vs HF group:(14 ± 4) mg×kg(-1)min(-1), P < 0.05]. (4) Both the mRNA and protein expressions of JAK2 and PTP-1B in FC group were significantly lower than those in HF group respectively.
Conclusion: There are insulin resistance and a high expression of JAK2 and PTP-1B in adipose tissue of obese rats induced by high-fat diet. And both are related with the elevated AngII level. Candesartan can reverse these effects.